Wind power generator equipped with a cooling system

ABSTRACT

A wind power generator has a nacelle; a hub rotatable about an axis of rotation with respect to the nacelle; at least two blades fitted to the hub; an electric machine which is fitted to the nacelle, is bounded by an inner surface extending about the axis of rotation, and has a rotor and a stator; and a cooling system for airflow cooling the electric machine, and which has a deflector body for defining a gap between the deflector body and the electric machine and guiding the airflow into the gap.

PRIORITY CLAIM

This application is a continuation of, claims the benefit of andpriority to U.S. patent application Ser. No. 12/485,645, filed on Jun.16, 2009, which claims the benefit of and priority to Italian PatentApplication No. MI2008A 001122, filed on Jun. 19, 2008, the entirecontents of which are incorporated by reference herein.

BACKGROUND

Known airflow cooling systems are not particularly efficient, especiallyin the case of generators equipped with a cylindrical electric machine.

SUMMARY

The present invention relates to a wind power generator equipped with acooling system.

More specifically, the present invention relates to a wind powergenerator comprising a nacelle; a hub rotatable about an axis ofrotation with respect to the nacelle; at least two blades fitted to thehub; an electric machine which is fitted to the nacelle, is bounded byan inner surface extending about the axis of rotation, and has a rotorand a stator; and a cooling system for airflow cooling the electricmachine.

It is an object of the present invention to provide a wind powergenerator equipped with a highly efficient cooling system.

A further object of the present invention is to provide a wind powergenerator equipped with a straightforward, low-cost cooling system.

According to one embodiment of the present invention, there is provideda wind power generator equipped with a cooling system, the wind powergenerator comprising a nacelle; a hub rotatable about an axis ofrotation with respect to the nacelle; at least two blades fitted to thehub; an electric machine which is fitted to the nacelle, is bounded byan inner surface extending about the axis of rotation, and has a rotorand a stator; and a cooling system for airflow cooling the electricmachine, and which comprises a deflector body for defining a gap betweenthe deflector body and the electric machine and guiding the airflow intothe gap.

According to the present invention, the efficiency of the cooling systemis improved by the entire airflow being forced into the gap, which runsclose to the electric machine and improves thermal exchange bypreventing part of the airflow from flowing too far away from thehottest parts of the electric machine.

Additional features and advantages are described in, and will beapparent from, the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described byway of example with reference to the accompanying drawings, in which:

FIG. 1 shows a partly sectioned side view, with parts removed forclarity, of a wind power generator in accordance with the presentinvention;

FIG. 2 shows a larger-scale lateral section of a detail of the FIG. 1wind power generator;

FIG. 3 shows a larger-scale view in perspective, with parts removed forclarity, of a detail of the FIG. 1 wind power generator;

FIG. 4 shows a larger-scale lateral section of a detail of the FIG. 1wind power generator.

DETAILED DESCRIPTION

Number 1 in FIG. 1 indicates as a whole a wind power generator, whichcomprises a pylon 2 extending along a vertical axis A1; a nacelle 3fitted to the top end of pylon 2 and rotatable with respect to pylon 2about axis A1; a hub 4 mounted to rotate with respect to nacelle 3 aboutan axis of rotation A2 crosswise to axis A1; and three blades 5, onlytwo of which are shown by dash lines in FIG. 1.

Pylon 2 is substantially defined by a hollow cylinder housing stairs(not shown in the drawings) and/or lifts (not shown in the drawings).

Pylon 2 is normally secured to the ground by a foundation (not shown inthe drawings). Alternatively, in off-shore systems, pylon 2 is securedto a floating platform (not shown in the drawings).

Nacelle 3 comprises a hollow body fitted to the top end of pylon 2 torotate about axis A1, and supports an electric machine 6 having a rotor8 and a stator 9, and bounded by an inner surface 7 extending about axisof rotation A2. In other words, electric machine 6 is a hollowcylindrical generator.

Likewise, hub 4 comprises a hollow body integral with rotor 8.

Wind power generator 1 comprises a cooling system 10 supported partly byhub 4 and partly by nacelle 3, and which serves to airflow cool electricmachine 6, and in particular to conduct an airflow, predominantly in adirection D1 parallel to axis of rotation A2, from an inlet 11 in hub 4to an outlet 12 in nacelle 3.

In the example shown in the drawings, stator 9 extends about rotor 8,and rotor 8 is integral with hub 4 and extends inside stator 9. Theinner surface 7 of electric machine 6 is therefore the inner surface ofrotor 8.

Stator 9 is fixed or connected directly to nacelle 3 along an innercylindrical surface of nacelle 3. Hub 4 and rotor 8 are connected toeach other and supported by a bearing 13 in turn supported by nacelle 3.

In a variation not shown in the drawings, the rotor extends about thestator, the stator is located inside the rotor, and the inner surface ofthe electric machine is defined by the stator.

Cooling system 10 comprises, in succession from inlet 11 to outlet 12,an air intake filtration device 14; a ventilation unit 15; and adeflector body 16.

With reference to FIG. 4, filtration device 14 is fitted to hub 4, islocated at inlet 11, and comprises a convex panel 17 located in front ofinlet 11 and having an outward-facing convex face 18 and anoppositely-convex annular edge 19; an annular panel 20 having a concaveface 21 extending about edge 19 and facing convex panel 17; and anannular panel 22 extending inside convex panel 17 and comprising aconvex face 23 facing convex panel 17, and a concave face 24 facing hub4.

Panel 17 is fitted to hub 4 by spacer arms 25, whereas panels 20 and 22are fixed or connected directly to hub 4 about inlet 11. Panels 17, 20and 22 are guide panels for guiding the air intake into hub 4, and aredesigned and positioned with respect to one another to define alabyrinth air intake path. Filtration device 14 thus prevents, or atleast reduces, entry of water, snow or impurities into hub 4 and nacelle3.

With reference to FIG. 1, ventilation unit 15 is housed inside hub 4,and comprises a powered fan 26; a guide 27 parallel to axis of rotationA2; and a slide 28 that runs along guide 27 in direction D1, andsupports fan 26.

Guide 27 comprises two rails 29 located about axis of rotation A2 andextending in direction D1. Fan 26 serves to increase airflow speed indirection D1 into nacelle 3.

Deflector body 16 serves to form a gap 30 between deflector body 16itself and electric machine 6, and to guide the airflow into gap 30.

As shown more clearly in FIG. 2, deflector body 16 is fixed or connectedto electric machine 6, in particular to rotor 8, by means of brackets31.

In the example shown in the drawings, and particularly in FIG. 1, rotor8 comprises a sleeve 32 supported by bearing 13 and integral with hub 4;a cylindrical structure 33 integral with sleeve 32; and permanentmagnets 34 fixed along the outer surface of cylindrical structure 33.Cylindrical structure 33 defines inner surface 7, which is a cylindricalsurface.

Cooling system 10 also comprises fins 35 parallel to direction D1 andfixed or connected to inner surface 7 of cylindrical structure 33.

Stator 9 comprises a stator pack 36 fixed or connected to the surface ofnacelle 3; and stator windings (not shown in the drawings).

With reference to FIG. 2, deflector body 16 is substantially axiallysymmetrical about axis of rotation A2, is fixed or connected to sleeve32 by brackets 31, and comprises a substantially conical central portion37 for guiding the airflow to inner surface 7 and defined by a centralpanel 38 and by a number of panels 39 extending about central panel 38;and a cylindrical portion 40 facing and parallel to inner surface 7, andwhich serves to define gap 30 and comprises a number of panels 41.Panels 38, 39 and 41 are connected removably to one another.

With reference to FIG. 3, fins 35 extend from inner surface 7 of rotor 8towards axis of rotation A2, and are divided into groups 42 and 43, eachof which, in addition to a given number of fins 35, comprises aperforated cylindrical sector 44 fixed by screws to cylindricalstructure 33. As shown in FIG. 3, fins 35 and respective cylindricalsector 44 are preferably formed in one piece.

With reference to FIG. 2, panel 38 is fixed or connected to panels 39 bymeans of thumbscrews 45, and comprises grips 46 by which to remove panel38 easily to allow access by maintenance personnel inside hub 4.

With reference to FIG. 1, fan 26 is movable along axis of rotation A2 toallow passage by maintenance personnel and also to set the fan to thebest operating position.

Cooling system 10 also extends partly outside nacelle 3, and comprisesfins 47 parallel to axis of rotation A2 and fixed or connected to theouter surface of nacelle 3, at stator 9, to assist cooling stator 9.

In actual use, nacelle 3 is oriented about axis A1 so that axis ofrotation A2 is positioned in the wind direction, with blades 5 into thewind, and the airflow therefore flows naturally along the labyrinth pathinto inlet 11, through hub 4 and nacelle 3, and out through outlet 12.At the same time, part of the air flows over the outer surface ofnacelle 3 and onto fins 47, which increase the air-stator 9 heatexchange surface.

Airflow inside hub 4 and nacelle 3 is also assisted by fan 26, whichserves to overcome any load losses in the airflow, and increases airflowspeed inside hub 4 and nacelle 3.

The airflow is diverted by deflector body 16, and assumes first apredominantly radial and then a purely axial speed component, both withreference to axis of rotation A2. That is, portion 37 serves to guidethe airflow to inner surface 7 of electric machine 6, and portion 40 ofdeflector body 16 to guide and keep the airflow close to inner surface 7of electric machine 6 and fins 35, so the entire airflow inside nacelle3 contacts the hottest parts of electric machine 6.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A wind power generator coolingsystem comprising: a deflector wall including a tubular portion,wherein: (i) at least part of the deflector wall is housed in a hollowelectrical machine of a wind power generator, the hollow electricmachine including: (a) a stator, (b) a hollow rotor which is distinctfrom the tubular portion of the deflector wall, and (c) an inner tubularsurface which extends about an axis of rotation, (ii) the deflector wallis mounted to the hollow rotor of the hollow electric machine, and (ii)a cooling airflow guide gap is defined between the deflector wall andthe inner tubular surface of the hollow electric machine, said definedcooling airflow guide gap extending between the hollow rotor and thedeflector wall.
 2. The wind power generator cooling system of claim 1,wherein the deflector wall includes a portion configured to direct acooling airflow to: (i) the inner tubular surface of the hollow electricmachine, and (ii) the tubular portion of the deflector wall.
 3. The windpower generator of claim 1, wherein the deflector wall includes aplurality of panels assembled adjacent to one another, and at least oneof said panels is configured to be removed.
 4. The wind power generatorcooling system of claim 1, wherein the inner tubular surface of thehollow electric machine is an inner tubular surface of the hollow rotor.5. A wind power generator hollow electric machine comprising: a stator;a hollow rotor housed within the stator and having an inner tubularsurface; and a deflector wall at least partly housed in the hollowrotor, said deflector wall including a tubular portion, wherein acooling airflow guide gap is defined between the deflector wall and theinner tubular surface of the hollow rotor, the deflector wall is mountedto the hollow rotor, and the hollow rotor is distinct from the tubularportion of the deflector wall.
 6. The wind power generator hollowelectric machine of claim 5, wherein the deflector wall includes aportion configured to guide an airflow to: (i) the inner tubular surfaceof the hollow rotor and (ii) the tubular portion of the deflector wall.7. The wind power generator hollow electric machine of claim 5, whereinthe deflector wall includes a plurality of panels assembled adjacent toone another, and at least one of said panels is configured to beremoved.
 8. A wind power generator cooling system comprising: adeflector wall including a tubular portion, wherein: (i) at least partof the deflector wall is housed in a hollow electrical machine of a windpower generator, the hollow electric machine including: (a) a stator,(b) a hollow rotor which is distinct from the tubular portion of thedeflector wall, and (c) an inner tubular surface which extends about anaxis of rotation, and (ii) a cooling airflow guide gap is definedbetween the deflector wall and the inner tubular surface of the hollowelectric machine; and a plurality of cooling fins connected to thehollow electric machine along the inner tubular surface.
 9. The windpower generator cooling system of claim 8, wherein the deflector wallincludes a portion configured to direct a cooling airflow to: (i) theinner tubular surface of the hollow electric machine, and (ii) thetubular portion of the deflector wall.
 10. The wind power generator ofclaim 8, wherein the deflector wall includes a plurality of panelsassembled adjacent to one another, and at least one of said panels isconfigured to be removed.
 11. The wind power generator cooling system ofclaim 8, wherein the inner tubular surface of the hollow electricmachine is an inner tubular surface of the hollow rotor.
 12. A windpower generator hollow electric machine comprising: a stator; a hollowrotor housed within the stator and having an inner tubular surface; adeflector wall at least partly housed in the hollow rotor, saiddeflector wall including a tubular portion, wherein a cooling airflowguide gap is defined between the deflector wall and the inner tubularsurface of the hollow rotor and the hollow rotor is distinct from thetubular portion of the deflector wall; and a plurality of cooling finsconnected to the inner tubular surface of the hollow rotor.
 13. The windpower generator hollow electric machine of claim 12, wherein thedeflector wall includes a portion configured to guide an airflow to: (i)the inner tubular surface of the hollow rotor and (ii) the tubularportion of the deflector wall.
 14. The wind power generator hollowelectric machine of claim 12, wherein the deflector wall includes aplurality of panels assembled adjacent to one another, and at least oneof said panels is configured to be removed.